This really doesn't apply to planes with multiple tanks, as the fuel shutoff generally does double duty as a selector.  But I have only one tank, so the cutoff valve is really only useful in case of an engine fire or in preperation of an emergency landing.

With a fuel pump that blocks flow when it isn't running, what useful purpose does the cutoff valve serve beyond increasing pilot workload?  Won't cutting power to the fuel pump provide the same service and eliminate several failure modes?